I just got an update of the official Ricoh Theta app in the Play Store.

The update description reads:

The video recording time per recording has been increased from 3 minutes to 5 minutes for the RICOH THETA (model: RICOH THETA m15).*Camera firmware needs to be updated to the newest version (Version 01.30 or higher).

So it seems there's a firmware update on its way to our devices. However, the firmware page still shows 01.21 as the latest version so does the firmware updater.